The Chinese scientist Ji Weizhi, a senior author of the study, and the Spaniard Juan Carlos Izpisúa. The risk is in opening up a path that other people could follow,” he reflected. “What they are aiming for is to be applauded, but perhaps one should also consider whether it could be used for other purposes, like creating some kind of in-between species.
There are, she added, “more ethically acceptable” alternatives to the use of monkey embryos.įederico de Montalvo, president of the Spanish Bioethics Committee and a professor of constitutional law at Comillas Pontifical University, asked why the experiments were carried out in China rather than in Spain or the United States: “Is it because they are scientifically more advanced or is it because ethically they are more relaxed?” De Montalvo is concerned about the unintended consequences of the research. “The results of the experiments are interesting, but justifying them in the context of regenerative medicine to generate human organs in animals for transplants seems to me a very distant goal,” she said. Mummery, of the University of Leiden (Netherlands), said that she felt unsure if the means justified an end that could be very far off for Izpisúa and his team. British biologist Christine Mummery, president of the International Society for Stem Cell Research, warned that human-animal chimeras “are crossing established ethical and scientific boundaries.” Her organization will issue new guidelines in May regarding this type of research. The announcement of the study’s results unleashed both stringent criticism and applause. The experiments were carried out at the Yunnan Key Laboratory of Primate Biomedical Research, a facility that holds thousands of monkeys in the Chinese city of Kunming. Nineteen days later, three of these embryos had reached the size of 10,000 cells, with human content of up to 7%.
MONKEY HUMAN CHIMERA SKIN
The team then took 25 human cells that had been reprogrammed back to an embryonic stage to make them capable of becoming anything from skin cells to heart or liver cells (known as induced pluripotent stem cells), and injected them into the monkey embryos. After six days of cultivation in the laboratory, they had obtained 132 embryos, each containing 110 animal cells. The researchers retrieved eggs from a dozen female crab-eating macaques and fertilized them with sperm from the same species. The scientists chose macaque monkeys for their next chimera study given the much closer genetic ancestry they share with humans, and with hopes of better understanding why the pig experiment failed. The team already announced the creation of rudimentary human-pig chimeras in 2017, but these contained barely one human cell for every 100,000 pig cells. Izpisúa’s group is made up of members of the Salk Institute for Biological Sciences in La Jolla, California, and of Murcia Catholic University (UCAM) in Spain. Growing organs in pigs would solve this problem, he believes. “Every year tens of thousands of patients die on the waiting list for an organ,” Izpisúa said. The World Health Organization (WHO) estimates that some 130,000 transplants are performed globally annually, but this is less than 10% of those needed. Izpisúa, 61, who is originally from Albacete in Spain, said that the real objective is the creation of human-pig chimeras, with the ultimate goal of growing human organs in pigs. Scientists use the term “chimera” from Greek mythology to refer to these hybrids, in reference to a creature with the head of a lion, a goat’s head on its back and a snake’s head for a tail. Three of the embryos, which grew to contain up to 10,000 cells, developed for 19 days outside the uterus, at which point the researchers interrupted the study, they said in an article published by the scientific journal Cell on April 15. A team of researchers led by the Spanish scientist Juan Carlos Izpisúa has created 132 human-monkey embryos in a laboratory in China, in a controversial experiment first revealed by EL PAÍS in the summer of 2019 and now officially published in detail.
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